In Patent Literature 1 and Patent Literature 2, catalyst-aided chemical processing methods are disclosed. Catalyst-aided chemical processing methods include using a catalyst composed of a transition metal that is disposed on a processing base surface, placing a workpiece in a solution that does not contain abrasive grains, etc., bringing the processing base surface into contact with or proximal to the processed surface of the workpiece, causing the processing base surface and the processed surface to move relative to each other, producing compounds in a chemical reaction between active species generated from the solution and surface atoms of the workpiece, and removing the compounds to process (etch) the workpiece; it is thereby possible to planarize (reduce the surface roughness of) a surface of difficult-to-process substrates made, for example, of SiC and GaN with high precision approximately at an atomic level.
Incidentally, as a method of causing relative movement of the surface of the pad, which is formed of a transition metal layer that serves as the catalyst layer, and the surface of the processed substrate (processed surface), which serves as the workpiece, a large-diameter circular pad is rotated on a platen, and the surface of the processed substrate, which has a smaller diameter and is held by a rotating holder, is brought into contact or proximity with a circumferential portion of the surface of the pad that is undergoing rotating movement, as shown conventionally in Patent Literature 1.